1. Field of the Invention
This invention relates to an all terrain vehicle and more particularly to the placement and orientation of the engine and type of engine and power train.
2. Description of Related Art
All terrain vehicles have become quite popular in Canada and the United States in recent years. The original vehicles were built with three wheels and had a chain drive. Motors were generally oriented in the vehicle, having the crankshaft and drive shafts oriented transversally to the direction of travel. Such vehicles were found to be unsteady and did not have sufficient stability and power to work as utility vehicles.
In more recent years, all terrain vehicles have been developed with four wheels for greater stability and in fact four wheel drive. Generally, the orientation of the motor was such that the crankshaft and drive shafts extended transversally to the line of travel and chain drives or other gear mechanisms were used to drive front and rear axles.
In very recent times, some manufactures have oriented the engine such that the crankshaft is parallel to the line of travel and the longitudinal axis of the vehicle. In fact, some vehicles have a single output or drive shaft which extends through the motor and drives transmissions on the front and rear axles. Being a single shaft of course the gear ratio is identical between a front portion of the single output or drive shaft and a rear portion of the single output or drive shaft.
Other problems with recent all terrain vehicles is the failure to provide access to the engine for maintenance and repair. It is difficult to access things such as the oil filter, engine oil filler cap or remove the cylinder head. Therefore, there is a need to have a vehicle with ready access to the engine.
Another problem with recently manufactured all terrain vehicles is that the engine is too high and takes up too much space. Therefore a new more compact engine is desirable. Another problem with present day engines is failure to have a parking gear. The parking gear is desirable when one wishes to keep the engine on or park on a steep slope. It is also desirable to have engine placement in such a way so that the vehicle can be easily mounted by the operator without stepping over a high straddle seat. Thus there is a need to position the engine such that one may step through to mount the saddle or seat.
The present invention provides a motor which is mounted in the vehicle under the seat. The vehicle has a step through passageway in front of the seat. The motor provides drive to the rear axle and front axle by means of two output shafts. The output shafts are connected to one another in a type of split shaft arrangement. Gears transfer power from the crankshaft to the transmission. Thereafter power is transferred to one output shaft and thereafter to the second output shaft. Each output shaft, i.e. the rear and the front, are directly in line with the differential gears on the rear and front axles respectively. Thus there is an ease of manufacture.
The transmission of the vehicle of the present invention consists basically of intermediate shafts and two transmissions. A parking gear is also provided to lock the two output shafts and prevents rotation with respect to the transmission housing.
The engine is located under the seat, while the gas tank is located just below the steering counsel. The seat is hinged and provides easy access to the engine. Since there is no fuel tank on top of the cylinder head it is easy to remove the cylinder head for maintenance or repair.
In the present invention the transmission is integrated into the crankcase of the motor. Positioning the crankshaft, balancer shaft and cam shaft roughly in the same area (although not on the same plane), the lowest overall height of the engine is obtained. The engine of the present invention has a two valve design. It is a four cycle engine with one cylinder. Two spark plugs are used.
An oil filler cap for the engine is located directly on top of the valve cover. Thus engine oil for the crankcase can be added with easy access. The oil sieve which is located on the bottom of the crankcase has an access cover and the oil sieve can be removed easily and cleaned.
The crankshaft of the present invention is connected to a centrifugal clutch. This is located forward of the crankcase between the clutch housing and the crankcase housing. Forward of the clutch housing is a clutch cover. A disengaging piston is found between the clutch housing and clutch cover. The all terrain vehicle uses a two clutch system which is well known in the art.
The present invention also has a parking gear. To the best of the inventors"" knowledge a parking gear has never been used before in an all terrain vehicle.
The transmission used in the all terrain vehicle of the present invention is located within the crankcase housing.
The water pump used for the engine coolant in the present invention is novelly positioned at the end of the crankshaft at the rear end of the crankcase housing. No other all terrain vehicle places the water pump directly on the crankshaft itself.
The radiator for the water cooled system is at the rear of the engine close to the water pump. The radiator also has a fan which is located at the rear of the vehicle""s engine.
The fuel tank has a low center of gravity and is positioned ahead of the engine. With regard to the air intake for the engine, it enters near the front of vehicle at the highest point to avoid water or mud entering the air intake. From there the air goes to an air box which houses an air filter and a silencer. Thereafter, the air is directed to the carburetor. The carburetor of the present all terrain vehicle is a standard carburetor.
The clutch housing and cover of the present invention is equipped with water coolant passages in the bottom. Water is routed through the bottom of the engine to cool the oil in the housing above. This is unique to all motor vehicle engines.
Therefore this invention seeks to provide an all terrain vehicle including a four cycle engine and a power train; said engine including a crankshaft; said engine being mounted in said vehicle such that said crankshaft is parallel to a longitudinal axis of said vehicle and parallel to a line of travel when said vehicle is in motion; said engine further including a rear output shaft and a front output shaft, said shafts being parallel to said crankshaft; wherein said rear output shaft in operation is adapted to supply power to a rear axle and said front output shaft is adapted to supply power to a front axle.